The present invention relates to dental handpieces, and more particularly to a dental handpiece which is freely rotatable relative to its air and water supply hoses and which is adapted to be quickly disconnected from the same.
Dental handpieces are widely used by dentists for drilling and cutting teeth. They are hand-held instruments which typically include a handle, a chuck mounted in the remote end of the handle, and an air driven motor for rotating the chuck. The chuck holds an interchangeable cutting bur. High speed handpieces have air driven turbine motors which rotate their cutting burs at speeds of 250,000 RPM or more.
One such high speed dental handpiece is the Model 5000 sold by A-DEC, Inc., 2601 Crestview Drive, Newberg, Oregon, the assignee of the present application. It has a screw-on type coupling which includes individual connections for supply hoses which deliver drive air for powering its turbine motor, and coolant air and water which are directed at the tooth being drilled.
Cross contamination is one of the principal problems encountered with dental handpieces. Bacteria and viruses can be communicated from patient to patient unless the handpiece is adequately sanitized. The safest and most desirable approach is to disconnect the handpiece from the air and water supply hoses and autoclave it after each patient treatment. Furthermore, in some instances it is necessary to couple a different handpiece to the supply hoses, e.g. one which operates at a relatively lower speed and at a higher torque for tooth cleaning. Therefore, it is desirable to provide a dental handpiece with a coupling which allows the handpiece to be quickly disconnected and reconnected to the air and water supply hoses.
The use of a high speed dental handpiece requires an extraordinary degree of manipulative precision. It is desirable to provide a dental handpiece with a coupling which allows the handpiece to freely swivel or rotate relative to the air and water supply hoses. Otherwise, the dentist must compensate for the torsional forces imparted by the supply hoses when manipulating the handpiece to drill or cut a tooth. Physical fatigue and occasional resulting cutting errors can be substantially reduced by making the handpiece freely rotatable relative to the supply hoses.
However, such a coupling must provide adequate seals for the drive air, coolant air, and coolant water connections. The coolant air is generally supplied at a higher pressure than the drive air. If coolant air should leak into the conduits for the drive air the delicate turbine motor may be driven at too high of a speed. This may result in damage to the delicate bearings of the turbine motor. If coolant water should leak into the drive air conduits, the turbine motor will not operate properly.